Calculations performed by a team of two mathematicians and an astronomer demonstrate how gas giants forming just a few astronomical units beyond the snowline could be thrust out to a hundred astronomical units and more.3 The thrusting mechanism they found to be especially effective was mean motion resonance, where the inner planet was much more massive than the outer one. Planetary mean motion resonance occurs when two planets orbiting a star exert a periodic gravitational influence on each other as a result of their orbital periods manifesting a ratio of two small integers (such as 3:2). In other words, with mean motion resonance each planet affects the orbit of the other. The strongest mean motion resonance takes place when the inner planet makes exactly two orbits for every single orbit of the outer planet—a one:two resonance.

Led by Aurélien Crida, the team showed that (under commonly expected conditions) a pair of planets formed in the 5–20 astronomical units region can be pushed out to a region up to ten times farther away from their host star. This result would explain––without the need to appeal to planet scattering––why the gas giants have been observed orbiting their star at great distances. For planet scattering to provide an adequate answer the planetary system must be comprised of closely interacting planets where the individual planets exhibit chaotic orbits.

The scenario developed by Crida’s team is testable. A gas giant planet has been discovered orbiting Fomalhaut (the brightest star in the constellation Piscis Austrinus) at a distance of 115 astronomical units. The researchers predict that a second, more massive, planet will be found orbiting Fomalhaut at a distance of about 75 astronomical units. Though difficult and time-consuming to detect, such a planet is discoverable with current instrumentation.

In their paper, Crida’s team declines to comment on the relevance of their discovery to the solar system and to life on Earth. Similarities and dissimilarities emerge.

Grade schoolers learn that Jupiter and Saturn dominate the Sun’s gas giant planetary system. Together these two planets account for 92 percent of the total mass of the Sun’s planets. As in the Crida team scenario, the Sun’s inner gas giant planet is the most massive. Jupiter is three and a third times more massive than Saturn.

Unlike in the scenario produced by Crida’s team, the solar system’s retinue of gas giants formed under exquisitely fine-tuned circumstances that placed them in the best possible positions to favor advanced life on Earth. This new research yields yet one more example of how the more we learn about planets, both solar and extrasolar, the more evidence we discover for the supernatural design of our Milky Way Galaxy and solar system for the specific benefit of the human race.

Subjects:
Astronomy and the Bible, Extrasolar Planets, Solar System Design

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. Read more about Dr. Hugh Ross.

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